When MPO solution was firstly introduced about 10 years ago, it brought tons of furor into the communication as well as the structured cabling industry, since the MPO solution initiated a new method to achieve higher transmission speed – using multiple parallel lines. Nowadays, MPO already becomes the predominant solution for data centers, and large enterprise cabling solution moves towards MPO as well, mainly due to daily increasing need of higher internet speed and the plug-and-play convenient installation nature of MPO solution.
Though MPO solution facilitates tremendously the installation, it causes some headaches for the designers, since to understand the polarity of the MPO channel is not that straightforward. In the ANSI/TIA-568 standards, three polarities were introduced for the MPO trunk cables, i.e. Polarity A, B and C, while two polarities for the MPO adaptors, i.e. Polarity A and B. The standards only illustrated two simple Polarity A and Polarity B MPO 40G channels, which is consist of three MPO trunk cables and two MPO adaptors. What if your systems are much more complex than this e.g. as shown below? What if you have mixed Polarity A and B components together, what will be the polarity of the channel then? Are there any tricks you can refer to when facing such scenarios?
Figure 1 Transceiver to transceiver with cross connect in the middle 
In white paper, a simple way is introduced to help you fast recognize the 40G MPO channel polarity. For more details, please refer to the white paper below.
Download the full article here:Introduction on 40G-100G MPO Configuration Website
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Source: Technical MMS Asia